High Strength Pipe Thread Protector

ABSTRACT

A device for protecting a portion of a pipe is provided. The device comprises a disk-shaped base having a proximal base surface and a distal base surface. An annular connector extends proximally from the base and has an interior connector surface and an exterior connector surface and a threaded engagement portion configured for threadably engaging the series of pipe threads. The device further comprises a ridge extending distally from at least a portion of the outer edge of the distal base surface. The ridge has a ridge height, an outer ridge surface and an inner ridge surface. The device also comprises a plurality of ribs extending distally from the distal base surface and radially inward toward the base axis from the inner ridge surface.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application No.61/552,783 filed Oct. 28, 2011, which is incorporated herein byreference in its entirety.

BACKGROUND OF THE INVENTION

The invention relates generally to the protection of pipe from damageand, more specifically, to a thread protection device (or “threadprotector”) for protecting end of a pipe and the threads adjacent theend of a pipe from impact loads.

Pipes, such as those used for oil or gas drilling, are often connectedat the ends using a male thread portion at one end (the pin end) of asection of pipe that is threadably engageable to a female thread portion(the box end) of another section of pipe.

The threaded ends of a pipe are subject to damage when not in actualuse. Pipes are often dropped or impacted by other outside forces.“Thread protectors” are commonly used to protect the threaded ends of apipe.

Thread protectors must prevent substantial impact energy from reachingthe pipe and damaging the threads during handling and transportation.This may be accomplished by a thread protector that plastically deformsupon impact, dissipating impact energy away from the pipe threads in theform of heat.

SUMMARY OF THE INVENTION

An aspect of the present invention provides a device for protecting aportion of a pipe having a pipe end, a pipe axis and a series of pipethreads adjacent the pipe end. The device comprises a disk-shaped basehaving a proximal base surface that faces the pipe end when the deviceis installed on the pipe and a distal base surface. The base is a bodyof revolution about a base axis that is coaxial with the pipe axis whenthe device is installed on the pipe. An annular connector extendsproximally from the base and has an interior connector surface and anexterior connector surface and a threaded engagement portion configuredfor threadably engaging the series of pipe threads for securing thedevice to the pipe. The device further comprises a ridge extendingdistally from at least a portion of the outer edge of the distal basesurface. The ridge has a ridge height, an outer ridge surface and aninner ridge surface. The device also comprises a plurality of ribsextending distally from the distal base surface and radially inwardtoward the base axis from the inner ridge surface.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention can be more fully understood by reading the followingdetailed description together with the accompanying drawings, in whichlike reference indicators are used to designate like elements, and inwhich:

FIG. 1 is a top view of a protection device according to an embodimentof the invention;

FIG. 2 is a section view of a protection device according to anembodiment of the invention;

FIG. 3 is a section view of a protection device according to anembodiment of the invention;

FIG. 4 is a top view of a protection device according to an embodimentof the invention; and

FIG. 5 is a section view of a protection device according to anembodiment of the invention;

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the present invention provides thread protectors that canbe threaded to the end of a pipe and that are able to withstand impactenergy from various angles and dissipate it in order to protect the pipeend and the threads at the pipe end. In particular, thread protectors ofthe invention are capable of meeting the requirements of AmericanPetroleum Institute (API) Specification 5CT/ISO 11960 Annex I, which isincorporated herein by reference. Thread protectors according to theinvention have structural features that allow reductions in the amountof material needed, which serves to minimize weight and productioncosts. The thread protectors of the invention may be made from a varietyof materials, depending on the desired strength properties and theanticipated environmental conditions in the field.

The thread protectors of the invention may be configured for threadableengagement with any standard threaded pipe. Throughout the presentspecification the terms “proximal” and “distal” are used to describe therelative placement and direction of features of the disclosed threadprotectors relative to the pipe when the thread protector is installed.As used herein “proximal” means in the direction the pipe extends fromthe pipe end and “distal” means in the direction away from the pipe, ineach case, along the centerline axis of the pipe. Thus, when installed,the proximal end of the thread protector is oriented in a directiontoward the pipe and the distal end of the thread protector is orientedin a direction away from the threaded end of the pipe.

In an illustrative embodiment of the present invention a threadprotector has a disk-shaped base with a proximal base surface and adistal base surface. The proximal base surface is attached to an annularconnector that extends proximally in the direction of the pipe. Theannular connector has an interior surface and an exterior surface and athreaded engagement portion for threadably engaging a correspondingseries of pipe threads adjacent the pipe end. The annular connector maybe configured as either a box or pin connector depending on theconfiguration of the pipe end. The illustrative thread protector has aridge that extends distally from the distal base surface. This ridge ispositioned along some or all of the circumferential edge of the distalbase surface. In some embodiments, the circumferential ridge may bebroken into a plurality of arcuate ridge sections. The ridge has aninner surface that is oriented toward and an outer surface that isoriented away from an axis of the thread protector that is coaxial withthe pipe centerline axis when the thread protector is installed. Theillustrative thread protector embodiment also has a plurality of ribsextending distally from the distal base surface. These ribs arepositioned and oriented so that they extend radially inward from theinner ridge surface toward the thread protector axis.

The illustrative thread protector will typically be a single integrallyformed molded thermoplastic material. Any suitable material providingthe requisite strength characteristics may be used. Typical polymermaterials may include but are not limited to high-density polyethylene(HDPE), low-density polyethylene (LDPE), polypropylene, nylon,polyurethane, and acetal. High strength HDPE, polypropylene, nylon andacetal may be particularly suitable.

The circumferential ridge and the ribs serve to support and reinforcethe base of the thread protector and distribute impact loads received bythe thread protector when installed on a pipe. The size andconfiguration of the ridge and the number, size and spacing of the ribsmay be varied depending on the design loads and other design criteria.In particular, these features may be determined based on an optimizationbetween expected environmental loads and material(s) used to produce thethread protector.

Aspects of the thread protectors of the invention will now be discussedin more detail. Referring now to FIGS. 1 and 2, a thread protector 100according to an embodiment of the invention for a pin end of a pipe isillustrated. The thread protector has a disk-shaped base 102, a proximalbase surface 102 a, a distal base surface 102 b, and an outer edge 102c. In this embodiment, the disk-shaped base 102 is a body of revolutionwith circular proximal and distal base surfaces. The base 102 may becylindrical or frusto-conical. In other embodiments, the disk-shapedbase 102 may be polygonal. The base 102 is a body of revolution about abase axis 108 that is coaxial with the pipe axis when the threadprotector is installed on a pipe. An annular connector portion 103extends proximally from the proximal base surface 102 a. The annularconnector portion 103 has an interior connector surface 103 a, anexterior connector surface 103 b, and a threaded portion 103 cconfigured to threadably engage the pipe threads of the pin end of apipe. As will be discussed, the annular connector portion 103 mayalternatively be configured for threadable engagement with a box end ofa pipe as exemplified by the connector portion 203 of FIG. 3.

With reference specifically to FIG. 1, a ridge 104 extends distally to aheight h from at least a portion of the distal base surface 102 b of thebase 102. The ridge 104 has an outer ridge surface 104 a and an innerridge surface 104 b and a width w. In this embodiment, the ridge 104 issubstantially circular and is co-centric with the circular outer edge102 c. In this embodiment, the width w and the height h are uniformaround the ridge 104. In other embodiments, either dimension may bevaried. As shown in FIG. 1, the ridge 104 may extend around the entirecircumference of the distal base surface. in other embodiments, theridge may be broken into arcuate segments.

The thread protector 100 has a plurality of ribs 106 extending distallyfrom the distal base surface 102 b and radially inward from the ridge104 toward the base axis 108. The ribs 106 may be evenly spaced withrespect to each other as shown or may have variable spacing.

The base 102, the ridge 104, the ribs 106, and the annular connectorportion 103 may collectively or individually be formed from any suitablematerial including composite resins, thermoplastics, polymer alloys,steel, or similar materials. In particular embodiments, the base 102,the ridge 104, the ribs 106, and the annular connector portion 103 maybe integrally formed as a single monolithic body.

The ribs 106 may be distributed around the entirety of the ridge 104 oralong one or more portions of the ridge 104. As shown in FIG. 1, theribs are distributed and evenly spaced in two distinct groups onopposing sides of the ridge 104. The specific configuration of the ribs106 may be determined based on the loads to be experienced and/or basedon tooling or manufacturing requirements. Each rib 106 has a length Land a width w₂. In this embodiment, the length L is the same for eachrib. In other embodiments, the length L may be varied from rib to rib,depending on the desired impact-load bearing and distributioncharacteristics of the thread protector. The width w₂ may similarly bevaried from rib to rib. Furthermore, in this embodiment, for each rib106, the width w₂ is uniform along the length L of each rib. In otherembodiments, the width w₂ may be greater at the end of the rib 106 thatis adjacent the inner ridge surface 104 b, with a gradual taper to asmaller width at the end of the rib that is closer to the base axis 108.This width w₂ may be varied based on the desired load-bearingcharacteristics of the thread protector. Each rib also has a height thatmay be the same as or different from the height h of the ridge 104.

Referring now to FIG. 3, an embodiment of a thread protector 200configured for protecting the threads on the box end of a pipe is shown.The thread protector 200 has a disk-shaped base 202, a circumferentialridge 204 and radially oriented ribs 206 that may be substantiallysimilar to the base 102, ridge 104 and ribs 106 of the thread protector100. The thread protector 200 also has an annular connector portion 203that projects proximally from the proximal base surface 202 a of thebase 202. The annular connector portion 203 has an interior connectorsurface 203 a and an exterior connector surface 203 b that includes athreaded portion 203 c configured to threadably engage the pipe threadsof the box end of a pipe.

The thread protector 200 FIG. 3 also includes an additional supportfeature that could be applied to either a box end protector or a pin endprotector. This feature comprises a plurality of support members 207 incontact with the interior connector surface 203 a and the proximal basesurface 202 a. The support members 207 extend proximally from theproximal base surface 202 a and radially inward from the interiorconnector surface towards the base axis 208. The support members 207 maybe equally spaced with respect to each other and may be distributedaround all or a portion of the circumference of the interior connectorsurface. In the illustrated embodiment, the support members 207 have acurved, buttress-like shape. It will be understood, however, that theshape of the support members may be varied depending on the desired loadbearing characteristics and the material used to form the threadprotector.

Again, the base 202, the ridge 204, the ribs 206, and the annularconnector portion 203 may collectively or individually be formed fromany suitable material. In particular embodiments, the base 202, ridge204, ribs 206, and connector portion 203 are integrally formed from athermoplastic material into a single monolithic body.

Referring now to FIGS. 4 and 5, a thread protector 300 according toanother illustrative embodiment is shown. The thread protector 300 has adisk-shaped base 302, a circumferential ridge 304, radially orientedribs 306, connector portion 303 and support members 307 that may besubstantially similar to those of the previous embodiments. The threadprotector 300 also has a number of additional features that may be addedindividually or collectively to the previously described embodiments.One such feature is a center hole 312 through the base 302, which isconfigured for receiving an engagement portion of a tool that may beused to assist in handling or installing the thread protector 300. Anannular hole extension member 310 has a center bore matching and alignedwith the center hole 312 and extends proximally from the base 302. Theannular extension member 310 has an inner extension wall 310 a and anouter extension wall 310 b. The center cylindrical hole 312 ispositioned coaxially with the base axis 308 so that a cylindrical toolportion can be inserted therein and the tool simultaneously rotatedabout the axis of the thread protector 300 and the axis of a pipe towhich the thread protector 300 is to be mounted. The thread protector300 may have, in addition to or instead of the center hole 312, one ormore off-center holes 311 through the distal base surface 302 b. Theseadditional holes 311 may extend through a portion of or all the waythrough the thickness of the base 302 and may be configured forreceiving engagement members of a tool for that may be used to assist inhandling or installing the thread protector 300. In a particularembodiment, the thread protector 300 has both the center hole 312 andtwo or more off-center holes 311, which are collectively configured forreceiving rotation members of a tool designed to engage the threadprotector, position it at the end of a pipe and rotate it to thread itonto the pipe.

Another optional feature of the thread protector 300 is the provision ofone or more tool engagement slots 314 in the circumferential ridge 304.These slots 314 may be provided and configured for application of arotational force on the thread protector 300 to install or remove thethread protector 300 from a pipe. In particular, these slots may beconfigured so that, in the field, any of a variety of tools notspecifically designed for use in conjunction with the thread protectorsof the invention may be used to provide torque to install or removethem.

In a particular embodiment, the ridge 304 of the thread protector 300 isbisected by a pair of tool engagement slots 314. The tool engagementslots 214 are positioned on a diameter through the base axis 208 onopposing sides of the ridge 204 to allow for the insertion of a bar orother tool found in a typical oil field environment. To facilitate theability to torque the thread protector by placement of a tool member inthe tool-receiving slots 314, the height h₁ of the ridge 304 may beincreased adjacent the tool-receiving slots 314 to h₂. This serves toincrease the bearing surface and the strength of the ridge 304 in theselocations.

It will be understood that any of the above optional features may beapplied to any of the embodiments described herein. Any of theembodiments described herein may be produced as a single integrallyformed monolithic structure. In particular, any embodiment may be formedby molding of a thermoplastic material. Features such as threads, holesand slots may be formed by molding or by machining of the molded part.

It will also be understood that the thread protectors of the inventionmay be scaled to any size as required for the protection of various pipediameters and thicknesses. The specific configuration and features ofthe thread protectors may be driven by the loads expected in use anddesired manufactured economies.

As has been discussed, the protection devices of the present inventionmay be formed from any suitable material. Particularly suitablematerials include various thermoplastic materials such as HDPE, LDPE,polypropylene, nylon, polyurethane, and acetal. Such materials may beprovided with any of various additives selected to enhance processingcharacteristics or to tailor the physical characteristics of the finalprotector device. Physical characteristics that may be tailored includematerial stability, coefficient of thermal expansion (CTE), strength andstiffness, and toughness. In some exemplary embodiments, an inorganic,halloysite-based, polymer additive marketed by Applied Minerals Inc.under the name Dragonite™ is added to an HDPE and molded to form threadprotector devices of the invention. In exemplary embodiments, LDPE.Filler materials or foaming agents may also be incorporated in some orall of the device components.

Exemplary thread protectors have been produced for a variety of pipesizes using HDPE. These protectors have been shown to withstand theaxial and angled load requirements of API 5CT/ISO 11960 Annex I undertest conditions ranging from −50° F. to 150° F. with no damage to thepipe to which they were attached. Thread protectors successfully metthese impact standards for pipe diameters ranging from 2.375 to 13.375in.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the method, manufacture,configuration, and/or use of the present invention without departingfrom the scope or spirit of the invention.

What is claimed is:
 1. A device for protecting a portion of a pipehaving a pipe end, a pipe axis and a series of pipe threads adjacent thepipe end, the device comprising: a disk-shaped base having a proximalbase surface that faces the pipe end when the device is installed on thepipe and a distal base surface, the base being a body of revolutionabout a base axis that is coaxial with the pipe axis when the device isinstalled on the pipe; an annular connector extending proximally fromthe base, the annular connector having an interior connector surface andan exterior connector surface and a threaded engagement portionconfigured for threadably engaging the series of pipe threads forsecuring the device to the pipe; a ridge extending distally from atleast a portion of an outer edge of the distal base surface, the ridgehaving a ridge height, an outer ridge surface and an inner ridgesurface; and a plurality of ribs extending distally from the distal basesurface and radially inward toward the base axis from the inner ridgesurface.
 2. A device according to claim 1 wherein the threadedengagement portion is a part of the exterior connector surface forthreadable engagement with a box end of the pipe.
 3. A device accordingto claim 1 further comprising: a plurality of support members extendingproximally from the proximal base surface and radially inward toward thebase axis from the interior connector surface.
 4. A device according toclaim 1 further comprising: means for receiving an engagement portion ofa tool configured for threading the device onto the pipe end.
 5. Adevice according to claim 1 further comprising: a plurality ofcylindrical holes through the distal base surface, said holes configuredfor receiving an engagement portion of a tool configured for threadingthe device onto or removing the device from the pipe end.
 6. A deviceaccording to claim 5 wherein the base has a base thickness and at leastone of the plurality of holes through the distal base surface extendsthrough less than the base thickness.
 7. A device according to claim 5wherein one of the plurality of holes through the distal base surface iscoaxial with the base axis.
 8. A device according to claim 7 furthercomprising an annular hole extension member extending proximally fromthe proximal base surface, the annular extension wall having an interioraligned with and in communication with the one of the plurality of holesthat is coaxial with the base axis.
 9. A device according to claim 1further comprising: a pair of tool engagement slots in the ridge, thepair of tool engagement slots being positioned on a diameter through thebase axis on opposing sides of the ridge.
 10. A device according toclaim 9 wherein the ridge height is greater in areas adjacent the toolengagement slots.
 11. A device according to claim 1 wherein each rib hasa rib height that is the same as the ridge height where the rib extendsradially inward from the ridge.
 12. A device according to claim 1wherein said base, said annular connector, said ridge, and said ribs area single integrally formed body.
 13. A device according to claim 12where in the integrally formed body is formed from a thermoplasticmaterial.
 14. A device according to claim 13 wherein the thermoplasticmaterial is selected from the group consisting of high-densitypolyethylene, polypropylene, nylon, and acetal.
 15. A device accordingto claim 13 wherein the thermoplastic material includes at least onepolymer additive.
 16. A device according to claim 1, wherein said devicemeets the impact loading requirements of API 5CT Annex I at temperaturesranging from −50° F. to 150° F.